Developing process



AU8- 22, 1944. J. RzYMKowsKl 2,356,536

l DEVELOPING PRocEss- Filed July 5, 1940 ffi i Patented Aug. 22, 1944 DEVELOPING PROCESS Johannes nzymkowskl, Jens, Germany; vestedin the Alien Property Custodian Application July 5, 1940, Serial No. 344,147.3 In Germany July 18, 1939 3 The present invention relates to a process of developing photographic pictureand sound-record copies in dependence Von the density of and/ or the contrasts in the negative. In carrying out the process according to the invention reversible y developers, i. e. oxidation reduction systems, are used the reduction potential of which is adjusted according to the density of and the contrasts in the negative respectively. 'I'his adjustment of the reduction potential may automatically be eilected according to the invention in dependence on the density of and the contrasts in the negative respectively. The mode of operation is applicable with equal advantage for copying and developing respectively of individual pictures and series pictures and particularly also of soundand sound picture-strips. f

-During the production of picture strips in the l nlm studio it cannotbe prevented that in alternate succession outside and inside pictures and scenes at night time, Le. under the most different conditions of illumination and ranges of objects are to be shot. After developing the negative,

therefore, one and the same nlm reel shows negative portions of most various densities.

To ensure a good reproduction it is absolutely necessary to equalize these differences as far as possible inthe positive nlm.

'I'his nrst has been tried by ascertaining the density of the essential points of the picture from one scene to another and then varying the light of the copying apparatus accordingly. This socalled ascertaining of brightnesses," however, proved to be too time consuming in practice. Thereupon on a photo-electric basis the density of the negative has continuously been scanned and the currents of the photo-electic cell have been used to control by way of relay or the like the quality or the brightness of the light of the lamp in the copying apparatus.

This compensation method, however, is under no circumstances perfect, because the following development is carried out with constant developer intensity regardless of what has previously happened with the negative or positive.

Here the process claimed as new starts.

By replacing the hitherto used irreversible developers by reversible systems it is rendered possible to adjust the reduction potential of the developer solution in dependence ou the density of the negative. In this manner the copy of a scene having large contrasts between light and shadow is tried to be equalized by a soit development, i. e. by a low reduction potential. Inversely it must be tried to enhance the contrasts in the positive by adjusting the reduction potential, ii for instance scenes are tobe copied which necessarily must be shot at fog.

Preferably as hitherto in carrying out the above mentioned primitive method of ascertaining ci.'y

brightnesses" the density of and the contrasts in the negative are not manually determined and the addition of the reduction agent necessary for the adjustment of the reduction potential also is not regulated according to circumstances from the outside, but the two operations are coupled i together. This mode of operation is of particular advantage in the electrolytic reduction of oxidation reduction systems. As is well known there are reversibly oxidizable developers and irrel versibly oxidizable developers.r The irreversibly y oxidizable developers hitherto quite generally have been used in the technics. To these developers belong the well known developers, as metol, hydrcquinone, pyrocatechin, rhodinal, glycine and so on. Samples of the reversibly oxidizable developers are the anthraquinones and anthrahydroquinones respectivelyvwhich hitherto had not been used as developers. As in the case of anthraquinones and anthrahydroquinones respectively oxidations and reductions respectively coupled with reversible operations are concerned, the oxidized as well as the reduced phase of the substance in question usually are present in the solutions. I

This mixture oi' the oxidized and reduced phase is the reason for the formation o! the potentials called oxidation-reduction-potentials. Suchmixtures or oxidation-reduction systems for instance are anthraquinones besides anthrahydroquinones, and indigo besides indigo white. Depending on the chemical nature of the substance and thel of the type Alk((R.COO)yMe), as iron citrates and the like. These oxidation reduction systems represent a mixture of the oxidized and reduced forms, the designation of the oxidation reduction systems always being eected according to the oxidation or O-form. In accordance with the invention such an oxidation reduction system is A' indamines, thiay I sible systems as developer is of importance, be-

cause in this manner only equilibrium may permanently be maintained and'finfluenced in any desired sense respectively. The usable oxidation reduction systems must be capable of being adsorbed by the silver halide and nucleus respectively.

Oxidation reduction systems capable of adsorption are only such systems which either are adsorbed by the latent picture of the metal salt layer or the metal salt itself. If for instance a silver halide layer, as silver bromide, is'exposed to light it adsorbs for instance the oxidation reduction system: anthraquinone/anthrahydroquinone, whereas the oxidation reduction system ferri-pyrophosphate/ferro-pyrophosphate is not adsorbed. If the rst mentioned oxidation reduction system is subjected to electrolysis the latent image is developed in the silver halide layl tion is diagrammatically shown by way of example. A

The negative film i is to be copied upon the positive nlm 2. rI'he negative nlm I is unwound from the supply roller 3 and passes along the source of light 4, whereby the oppositely arranged photo-electric cell 5 is energized in accordance with the density of the nlm portion just situated between the source of light and the photo-electric cell. By way of a relay 6 the current coming from the photo-electric cell 5 may control the brightness of the copying lamp l. By way of a relay 8 and a resistance 9 this current may also be used to control the current of the electrolysis which is derived from the source of current I0. This current effects electric development in the container Il in which the positive nlm 2 slowly and continuously is passed over rollers i3, Il and i5.' The currents of the photo-electric cell 5 may be supplied as desired to the two relays 6 and 8, or, by the aid of the circuit breaker i2, the relay 8 and thereby the current serving for the development may be controlled. The operation is such that if the negative is rather flat a more intense current is used for the electrolysis, whereas for negative portions .with large contrasts the current intensity is automatically reduced. The control of the reduction potential, however, may also be combined with the arrangement of the copying light 1. Instead of the device for eil'ecting electrolysis shown in the example, the potential of the oxidation reduction system may permanently be maintained by blowing gaseous hy,

drogen into the development vessel which is provided with one or more catalyzers. The relay I then does not operate a regulating resistance, but the reducing valve of a hydrogen bomb.

This automatic regulation of the current of electrolysis or of the reducing agent may advan- N tageously be effected by control records the contrasts of which are arranged in dependence on the density of or the contrasts in the negative.

By lifting and lowering the rollers I3, i4 and l5 the film may remain in the electrolyte for a shorter or longer period of time respectively. As the reduction potential of the development vessel, controlled by the photo-electric cell, may, in dependence on the size of the system, operate eventually with a certain inertia, the way the nlm mustperform from the point of copying to the development vessel must be chosen of such length that thelreductlon potential always is adjusted in the development vessel as soon as theA corresponding scene is introduced into the development vessel. This is obtained by correspondingly choosing the length of way between the point of copying and the development vessel. Therefore, in the example illustrated in the drawing one or more film loops may be provided as indicated by the interruption of the path of the film 2 at I6 between the point of copying 1 and the development vessel Il. Moreover, instead of -a single electrolyzer several electrolyzers, united to an aggregate, may be provided each of which preferably has the form of a tube.

Since oxidation reduction systems are, as is well known, pH-sensible, it is possible to use the currents coming from the photo-electric cell 5 for iniluencing the pH-value, for instance in such a manner, that such currents control the valve by way of which acid is continuously supplied to the development vessel. In connection with some oxidation reduction systems it is advisable to use the photo-electric cell to simultaneously control the current of electrolysis. the copying light and the pH-value, whereby preferably current regulating resistances are arranged in the circuit of the three relays. In the drawing the regulation on the pH-value is not shown.

The other modes of operation for developing by means of oxidation reduction systems capable of adsorption the reduction potential of which is, during development, maintained or adjusted at times may, of course, all be used in connection with this mode of operation. The mode of operation, moreover, is not limited to the use of definite oxidation reduction systems and also not to the development of silver halide layers as other photographically usable metal silver layers, as for instance mercury halides, thallous halides, complex cobalt salts etc., may be used in Ithe same manner.

In the drawing the picture negative only has been indicated. In a. corresponding manner the sound negatives also are copied and finally, by the use of a corresponding copying apparatus, the picture negative as well as the sound negative may be copied upon a common positive nlm. Special scanning members connected to photo electric cells will be provided for the picture negative and for the sound negative respectively.

By this mode of operation it is possible to obtain the most suitable y-value of the sound strip and of the picture in the developed positive nlm. In particular the entire sound strip of the developed film roller is maintained constant in an excellent manner. Hereby the old drawback of sound fluctuations occurring when projecting films in cinemas is strongly. opposed.

The new method may also be used in connection with color films by selectively adjusting to an optimum either the color development of the picture or the silver-and silver sulphide precipitate respectively of the sound strip. It is of no importance, whether the natural color picture is produced in one layer or in several superposed layers. A modification of this photoelectrically controlled color development consists in using in the development vessel oxidation re- -phenols,l aminoindophenols, or these oxidation reduction systems as indophenols, aminoindophenols, indamines respectively are electrosynthetically to be produced from preliminary products not developed, this production` eventually being carried out in the development vessel. The coupling components necessary to obtainthis production may be present either in one layer.

or in a plurality of layers of the metal salt layers f of the lm, i. e. in the film itself or else in the development vessel itself.

The precipitation of the foreign ions, for instance halogen ions, is chemically or electrochemically eiected in the usual manner.

What I claim is:

1. A method of producing photographic picture and sound record copies from a negative comprising photo-electrically scanning said negative, exposing a positive lm to light transmitted through said negative while controlling the intensity of said transmitted light in accordance with the electric energy created during the scanning of the negative, and developing said exposed positive film'in an oxidation reduction system capable of adsorption while controlling the reduction potential of said system in accordance with the electric energy created during the scanning of said negative.

2. A method o! producing photographic picture and sound record copies from a rmoving negative film strip comprising photo-electrically scanning the adjacent frames of said negative in succession, successively exposing adjacent frames Vof a positive nlm strip to light that is emitted by a source other than the source used in scanning and that is transmitted successively v through the adjacent scanned frames of said negative,v and successively developing each exposed frame of said positive in an oxidationreduction system capable of adsorption while controlling the reduction potential of said system in accordancek with the electric energy created during the scanning of the corresponding frame of said negative.

- 3. A device for copying moving negative strip film onto moving positive strip film comprising an electric circuit having photo-electric cell means positioned to scan the adjacent illuminated frames of said`negative in succession as the negative moves, a copying light source positioned to successively transmit light through each adjacent scanned frame of the moving negative and onto adjacent frames of the moving positive, oxidation-reduction developing means for successively developing the adjacent exposed frames of the positive and through which the exposed positive is moved, electric circuit means for varying the potential of said developing means, relay means in the photo-electric cell circuit for successively controlling the intensity of the copying light in accordance with the electric energy created by the successive scanning of the adjacent frames of said negative, and second relay means for controlling the variation of said potential in accordance with the electric energy created by the successive scanning of the adjacent frames of said negative, said two relay means being in parallel connection with 'said photo-electric cell means.

J OKHANNES RZYMKOWSKL 

